Demands made upon data transmission systems are on the increase. This concerns particularly wireless digital data transmission systems, such as cellular radio systems, which are expected to produce increasingly complex services, for example various data services.
A typical cellular radio system comprises a fixed base station network in which a subscriber terminal communicates with one or more base stations of the system. Furthermore, the cellular radio system comprises a base station controller which controls the base stations, and a mobile services switching centre. In connection with the cellular radio system, it has been known to connect a plurality of base stations of the cellular radio system so as to enable a plurality of base stations to be controlled by one base station controller by means of telecommunication connections by fixed connections, such as cabling or fixedly installed radio links.
It is previously known that a transmission connection between network elements is typically implemented using a 2Mbit/s connection, i.e. a PCM (Pulse Coded Modulation) link. At worst, the 2 Mbit/s PMC link used by the operator for transmission is so occupied that the increase in capacity mentioned above would require a new PCM link to be introduced. This would be both expensive and difficult.
The prior art solutions allow the number of telecommunication connections between the base stations in a network, i.e. the network configuration, to be manually changed in such a manner that the maintenance personnel visits all base stations to be changed. This is laborious, and such a prior art system does not enable the structure of the network to be flexibly changed. For example, it is thus impossible to change the transmission capacity of different base stations daily according to the base station which has the heaviest traffic. It would be most desirable that mobile telephone operators in urban and suburban areas should have such a characteristic.
Another disadvantage of the prior art system is that owing to the manual configuration of the network transmission connections, the prior art network is difficult to manage since the network cannot be managed from one point but the base stations have to be separately visited when the network configuration is to be changed.